Vibratory conveyor sand seals for pusher type furnaces



Dec. 15, 1959 E. H. KENDALL VIBRATORY CONVEYOR SAND SEALS FOR PUSHER TYPE FURNACES Filed April 6, 1956 ATTO EY 2,917,298 Patented Dec. 15, 1959 VIBRATORY CONVEYOR SAND SEALS FOR PUSHER TYPE FURNACES The present invention relates to the furnace art in generall and more particularly to improved sand seals for use in a pusher type furnace. These improved sand seals have utility in the furnace art and especially when applied to furnaces of the type where successive bogie carts are pushed through an elongated heating chamber in endto-end relation by suitable pushing means.

Although the pusher furnace of the type to be further described is commonly used for the heating of metal objects, these installations are relatively inefficient when the problem of providing proper seals between the bogie carts and the side walls of the furnace is considered. It is imperative that effective seals be maintained as they prevent the escape of heat to the surrounding cooler air thereby cutting down the fuel costs, protect the main structural parts of the bogie carts from excessive heat, and allow considerable conservation of insulating materials when the heating chamber-is being built. Heretofore, the seals used have consisted of elongated troughs fastened to the buckstays or supporting frame of the furnace and extending the entire length thereof. The troughs are filled with sand or other loose granular material having heat resistant qualities while the bogie carts are fitted with cooperating side plates which, when thecar is in the heating chamber, drag in the sand thus completing the sand seal. As the Asand troughs extend the entire length of the furnace, and each bogie cart is equipped with the cooperating side plates, the seal is continuous even when the carts are being pushedor moved through the heating chamber.

This sand sealing means has been practically universally accepted in this art even though there are serious ineiciencies and resulting complications from its use. The main problem encountered is that the sand is carried through the troughs in the direction of cart travel by the effect of the dragging side plates. This necessitates collecting the sand at the discharge end of the furnace and transporting it back to the loading entrance for refilling of the troughs. lf this operation is not performed with some degree of regularity, much of the sand soon becomes forced out the discharge opening of the furnace and as a result the seal is broken because there is not the required depth of sand in the troughs.

It is therefore an object of the invention to provide` an effective sand seal between the bogie carts and the side walls in which the movement of the sand in the troughs to the discharge end of the furnace is substantially eliminated. In this manner, the troublesome and bothersome detail of refilling the sand troughs is eliminated.

Yet another object ofthe invention is the provision of an improved sand seal between the side walls of the furnace and the bogie carts wherein the sand is evenly distributed in the troughs throughout their length. It is also another undesirable characteristic of sand seals not embodying the invention disclosed herein that the sand tends to collect and pile up at certain points along the troughs. Many times this action means there is not enough sand some places and too much at others causing only sporadicv seals to be formed.

A further object of the invention is to provide a sandy seal trough utilizing what is commonly known in the transporting art as a vibratory conveyor to accomplish the above stated objects. The vibratory conveyor moves. the sand in the opposite direction of the bogie cart travel, 'It is in this manner that a continuous seal is provided regardless of the effect of the plates attached to the bogie carts being dragged through the sand.

An important consideration, having considerable bearing on the intended use of the seal, is that the pusher type furnace is usually employed in a sustained and continuous manner. This is particularly true where the heating furnace is an integral part of a processing line. The sand seals I have provided are therefore of rugged and durable construction so as to require verylittle attention or maintenance during heating operations.

The above, as well as other objects and advantages of the invention, will become more fully apparent upon consideration of the following detailed specification and the accompanying drawing wherein is found a specific illustrated embodiment of the invention.

In the drawing:

Figure l is a side view, partially in section, of the pusher type furnace employing the vibratory conveyor sand seals constructed in accordance with the teaching of my invention;

Figure 2 is an end sectional View of the furnace assembly in Figure l; and

. Figure 3 is an enlarged partial end view of the apparatus shown in Figure 2 depicting specifically the vibratory sand seals.

Referring now to the drawing wherein is shown an illustrated embodiment of my invention, the numeral 10 designates generally a pusher type furnace consisting of elongated and spaced side walls 11 and 12 joined by an arched roof, these elements being constructed from heat refracting and insulating material such as lire brick, for example. The side walls 11 and 12 as well as the roof 13 are supported by various structural frame members or buckstays 14 which provide both vertical and lateral strength to the rfurnace assembly. AIn addition to the buckstays 14 a plurality of vertical supporting members 15 further add rigidity to the furnace and serve to carry the sand troughs of the present invention as will be hereinafter more fully explained. The furnace 10 is built over a pair of longitudinally extending rails 16 on the iloor or concrete base of a plant, for example. This structure, consisting of the side walls 10 and 11 and the arched roof 13, forms an elongated heating chamber with charging and discharging openings 18 and 19, respectively, at either end thereof.

Bogie carts, such as the one shown at 17, are adapted to be moved through the furnace 10 along the rails 16 in end-to-end relation forced by some means, such as a pusher rod, not shown. It is usual practice to load workpieces to be heated on the bogie carts and then push the carts in a line through the furnace with the furnace being at such a temperature that the workpieces will have obtained the desired temperatures by the time they reach the discharge opening 19 at the far end of the furnace installation.

This type of a bogie type pusher furnace is known to be an expedient heating plant, being generally accepted in the art. In many instances, the furnaces are of considerable length, depending on the type and quantity of material being heated and the temperatures required. In n burner ports situated at spaced points along the sideV wall 11 and 12 throughout the length of the furnace. Also associated with the burners are fuel-and compressed air conduits to supply the proper combustible mixture to the burners and exhaust manifolds to carry away the spent fumes. Depending on the specific use of the furnace, suitable means for loading and unloading the workpieces are provided adjacent the charging and discharging ends 1S and 19, respectively of the furnace and sorne arrangement must also be incorporated for returning the bogie carts from the discharge end 19 to the charging entrance 18 of the furnace for re-entry thereinto other than the rails Y16 for sustained and continuous operations. In the construction of the vibratory sand seals of the present invention, I provide upturned channels forming sand troughs 2? positioned below the refractory side walls 11 and 12 and extending the entire length of the furnace on both sides thereof. Each trough 20 has flanged lip portions 21 which cooperate with longitudinally extending and rigidly attached side supports 22 in supporting the trough 26. Bolted or held by some other attachment means tothe inside face of the supports 22 are a pair of downwardly angled plates 23 mounting, at their extreme downward end, a vibrator unit 24. Each of the vibrator units 24 comprises a main frame 40 and a forwardly projecting armature 41 which is attached to the downwardly angled plates 23. The vibrator unit is such that the armature is movable with respect to the main frame and imparts vibratory conveyor movement to the sand trough. It is noted from the side View, Figure l, that more than one vibrator unit 24 is contemplated for each trough, a plurality of these members being attached at longitudinally spaced points via the angled plates 23 in driving relation with each trough and the final number being determined by the overall length of the trough 20 and other considerations to be hereinafter more fully described.

For mounting the vibratory units 24, an elongated angle 25 is fastened to one side of the vibrator units 24 and extends the length of the trough 26 and is adapted to be fastened at spaced points to a like angle 26 projecting from the vertical supports 15. A similar angle 27 may be attached to the opposite sides of the vibrator units 24 and is supported at spaced points by vertical posts 28. Thus, the armatures 41 of the vibrator units are attached to the sand troughs via the angled plates 23 for vibrating the troughs while the frames 40 of these units are rigidly and securely attached to the structural framework of the heating chamber. derstood, however, that any means of support whereby the sand troughs 20 are carried by the vibrator means which in turn are supported by the buckstays or other rigid supports from the furnace walls is entirely within the scope of the invention.

Vibratory units 24 are electrically powered and are of the kind Well known in the art suitable for use in driving various feeding mechanisms. As such, the armatures of the units have a relatively slow movement in one direction and a quick return movement and, of course, this lcharacteristic is so oriented that the troughs 2t) move more slowly in a longitudinal direction opposite to the -direction of movement of the bogie carts through the furnace. This relatively slow movement tends to move the sand toward the charging end of the furnace chamber, and equalizing movement of the sand in the opposite direction during a vibratory cycle is impeded by the inherent inertia of the sand mass during the quick return movement of the troughs.

The sand troughs 20 are lled with sand or some other loose granular material having heat resistant qualities and to complete the seal some type of projection must extend from both the side walls and the bogie carts 17 into the sand. In the illustrated embodiment, see Figure 3, each of the side walls 11 and 12 are further'supported by a plate 29 resting on an angle 3i) attached to the buckstays 14. A. T-shaped member 31 has one leg thereof It should be un- 4 pinched between the side wall 11 and the plate 29 while another leg extends into the sand carried in the trough 20. It is contemplated that the member 31 will extend the length of the furnacethus completing an effective sand seal between the side wall of the furnace and the trough the entire length of the heating chamber.

Much of the same construction is also applicable for effecting a seal between the bogie carts 17 and the sand in the trough 20. Each bogie cart consists of a structural frame 32 mounted on wheel and axle assemblies and carrying a refractory top 34 of fire brick or other insulating material which also may have a chrome ore hearth 35 therein forming the workload supporting bed of the cart. A pair of T-shaped members 36 are positioned on both sides Yof the cart so that one projection of each member 36 is pinched between the refractory top 34 and the structural frame 32 and another portion thereof extends into the sand carried in the sand trough 26. Because every bogie cart is provided with the members 36 on both sides thereof and the members are as long as or slightly longer than the length of the carts, a continuous sand seal is formed between the carts and the troughs when the bogie carts are being pushed in end-to-end relation through the furnace.

In the operation of the new and novel vibratory sand seals, it is assumed that the troughs 20 have been filled with sand to a level where the projecting ends of the T-shaped members 31 and 36 are substantially covered. As the bogie carts 17 are pushed through the furnace, it has been found that the sand is carried toward the discharge opening 19 of the furnace requiring reloading of the sand troughs, and in many cases breaking the seals. This problem is eliminated in my apparatus by providing the vibrator units 24 which are operative when activated to vibrate the troughs 20 andV consequently to move the sand contained in the troughs in the opposite direction to the direction of bogie cart travel thereby counteracting the effect of the member'36 being dragged through the sand. In this manner, by vibratory movement of the troughs 20 by the vibrator units 24, the sand remains in relatively the same place as the effect of the bogie carts dragging the sand and the vibratory units operating to move the sand in the opposite direction counteract each other. It is contemplated that control equipment, not shown, such as potentiometers or rheostats, will be provided to control the speed of the vibrator units so that they may be easily energized and deenergized or controlled as the need arises to keep the sand in relatively the same position. Obviously, when the bogie carts are not being pushed through the furnace, the vibrator units 24 will be deactivated lest the sand be forced out the charging opening 1S of the furnace.

Although the main function of the apparatus described is to keep the sand evenly distributed in the troughs, the vibratory units may be used and operated at certain times to completely remove the sand from the troughs without shutting down the furnace installation which may be desirable once the sand has become mixed with iiash and refuse from the furnace. In this case, the vibratory units are run at a high rate of speed until all the sand has been removed while clean sand may then be fed into the troughs at the discharging end 19 of the furnace and the vibrator units willl move the troughs in such a manner as to distribute the sand evenly throughout the length thereof.

It should thus be apparent that I have accomplished the objects initially set forth by providing for a vibratory sand seal for a pusher type furnace which eliminates any need for collecting the sand at the discharge end and refilling the sand troughs at the charging end. There are several ancillary benets resulting from the use of this type of sand seal which allow more ellicient furnace operation. Probably the greatest benefit is the saving of fuel necessary to bring and maintain the furnace at a desired temperature, which over a period of time may be considerable. The sand seals are always effective throughout the length of the furnace and the escape of the heat to the cooler air under the bogie carts is precluded. Another advantage of insuring continuous sand seals is that the undercarriages and structural platforms of the bogie carts are better protected from exposure to excessive heat thus prolonging their operating life before they require repair or replacement.

I have provided apparatus that insures that the sand is evenly distributed throughout the length of the troughs thereby realizing effective seals along the entire length of the furnace. In accomplishing this and the other objects of the invention, I have taught the mounting of the sand troughs by vibratory conveyor means which in turn are toward the charging end (opposite the direction of bogie cart travel) thereby counteracting the effect of the sealing plates of the bogie carts carrying the sand toward the discharge end of the furnace. It is further observed that the configuration and construction of the sand seals disclosed herein is rugged and durable so that they may be operated in a continuous manner and require a minimum of maintenance and repair.

Although I have described a specific embodiment of the invention, it should be understood that many changes may be made therein without departing from the scope of intent of the invention and therefore reference should be had to the following appended claims in determining the full coverage of the invention.A

I claim:

l. In a furnace installation comprising an elongated heating chamber built over a pair of parallel rails and f having insulated and refractory side walls, a plurality of bogie carts adapted to be moved through said furnace in end-to-end relation, and sand seals for sealing said furnace from below to protect the structural portions of said carts and prevent the escape of heat from said heating chamber; the improvement in said sand seals comprising elongated said troughs on either side of and extending the length of said furnace, means attached to said bogie carts to drag in said sand troughs whereby a continuous seal is formed, and means to vibrate said sand troughs whereby the eiect of said means attached in dragging the sand through the troughs is counteracted.

2. In a furnace installation comprising an elongated heating chamber having insulated and refractory side walls, bogie carts having load-supporting hearths, said carts adapted to be moved through said chamber in successive end-to-end relation, and sealing means for sealing said furnace from below; the improvement in said last mentioned means including elongated troughs on either side of and extending the length of said chamber, said troughs adapted to be lled with loose granular heat insulating material, means attached to said carts operative to extend into said troughs when said carts are within said chamber, and means to vibrate said troughs longitudinally in the direction of travel of said carts to counteract the effect of said means attached in dragging said material through said troughs.

3. In a furnace having a movable hearth and means to seal said furnace from below, said means comprising a pair of troughs on either side of and extending the length of said furnace, said troughs adapted to be filled with sand or other loose granular heat insulating material, means attached to said hearth adapted to cooperate with and extend into said troughs to form a continuous seal, means supporting said troughs for vibratory conveyor movement, means to control the vibratory conveyor movement of said troughs, said means supporting comprising a vibrator conveyor unit for each of said troughs, said unit having a frame portion and an armature, said armature being attached to and supporting the trough associated therewith, and said frame portion of said unit being rigidly attached to said furnace.

4. Apparatus according to claim 3 further characterized in that each of said troughs has a pair of downwardly angled plates extending from the sides thereof, said vibratory conveyor unit being mounted directly be neath said trough in nesting relation therewith, and said armature of said unit being attached to said downwardly angled plates.

References Cited in the le of this patent UNITED STATES PATENTS y 1,698,835 Weiser Jan. 15, 1929 1,825,380 Alinder et al. Sept. 29, 1931 2,367,063 Shallock Jan. 9, 1945 2,420,126 `Currll et al. May 6, 1947 

